The 26-year-old Chinese world champion beat her rivals with a score of 394.40 to end the semi-final 32.3 clear of her nearest rival Tania Cagnotto.
That would seem likely after she finished so far ahead of Italy's Cagnotto, aiming for her first Olympic medal at her fourth Games, with He third after she made some uncharacteristic mistakes.
Cagnotto is bidding to join her father and coach Giorgio, who won four Olympic medals between 1972 and 1980, in making the podium but admitted the gold was Wu's to lose.
I am very happy, but tomorrow in the final I will start againTania Cagnotto
'I am very happy, but tomorrow in the final I will start again,' she said.
'I am not competing with Wu as she is very strong but today the other Chinese diver He made a mistake and it allowed me to come second. So we will have to see what happens tomorrow.'
Canada's Jennifer Abel, who won bronze at last year's World Championships, qualified fourth but said she was not expecting to win a medal.
The 20-year-old has already stood on the podium in London, after winning bronze alongside Emilie Heymans in the women's Synchronised 3m Springboard on Sunday, and would appear to have room for improvement after a couple of errors.
'I'm hoping to stay around fourth, but if I do better and end up on the podium I'll be very happy, but it's not my objective,' she said.